Android will block a number you do not want to receive calls. This requires go to your contacts. View the contact card you want to block. Press the "Menu" button on your smartphone and check the "All calls to e-mail." All calls from this contact will be directly forwarded to your voice mail. If you want to block several numbers, you can create a contact for each number and then block it, or else simply create a contact "black list" containing all the unwanted numbers then block that contact.
If your smartphone is the Samsung brand, LG, HTC or your smartphone can handle a reject call list from the parameters of the Phone application. Start the application and press the "Menu" key and click on the "Settings" option.
Play Store also contains many applications adding a list of calls to reject. The security application "Avast! Mobile Security" has this feature, and also allows users to select the time of day or week during which the filtering is effective. There are also applications exclusively dedicated to this treatment as "Call blocker" or "Blocking Calls and SMS." You can easily find them by searching the term "Call Blocker" in the Play Store.